Joseph Woo, MD, the chair of cardiothoracic surgery at Stanford, recently sat down with me to discuss his Nov. 2017 study on new evidence for helping heart patients decide between mechanical or biological valve replacements.

Because of design limitations of each valve type, it’s a complex choice influenced by a patient’s anticipated lifespan and lifestyle. Mechanical valves may last a lifetime, but they come with an increased risk of blood clots, necessitating the long-term use of blood thinners. Biologic valves made from pig or cow tissue typically don’t cause clotting, but they wear out sooner, often requiring patients to undergo another surgery.

To help with this decision, Woo and his team analyzed outcomes data from the electronic health records of more than 25,000 patients who underwent heart-valve surgery at 142 hospitals in California between 1996 and 2013. They looked at the rates of mortality, stroke, bleeding and repeat operations.

The team’s findings, which overturned recommendations established more than 30 years ago, showed that mechanical heart valves may be safer in certain cases than valves made of animal tissue and should be used more in younger patients. His results also showed that for patients undergoing mitral valve replacement, a mechanical valve is beneficial until the age of 70.

When asked what was noteworthy about this study, he said, “It demonstrated how data within electronic health records can be analyzed with advanced statistical methods to answer important clinical questions when a randomized study is impractical or unethical.”

On April 18, Woo and his team will receive a 2018 Top Ten Clinical Research Achievement Award for this research. Awardees were selected by the Clinical Research Forum, a national organization that honors the most innovative and impactful peer-reviewed studies published in the prior year.